[18F]-FDG PET/CT in oncologic patients with unsuspected asymptomatic infection with SARS-CoV-2

Abstract

Purpose: Spain has been one of the most affected countries by the COVID-19 pandemic, being among the countries with worse numbers, including the death rate. However, most patients are asymptomatic, although they are very contagious. The objective of this study was to investigate the incidence in oncological patients infected with SARS-CoV-2 that are asymptomatic for COVID-19 and at home and that undergo PET/CT for oncologic indications, nonrelated to COVID-19, finding in the PET/CT lung alterations that are suggestive of SARS-CoV-2 infection.

Methods: During the period of maximum incidence of the global pandemic in one of the most affected regions of Spain, there were 145 patients that met inclusion and exclusion criteria and were included in the study. Imaging findings previously described such as ground-glass opacities with low [¹⁸F]-FDG uptake were considered images suspicious for SARS-CoV-2 infection. Patients with these findings were referred to RT-PCR testing and close follow-up to confirm the presence or absence of COVID-19.

Results: Suspicious lung imaging findings were present in 7 of 145 patients (4.8%). Five of these 7 patients were confirmed as presenting SARS-CoV-2 infection, this is, COVID-19. In the remaining two, it was not possible to confirm the presence of COVID-19 with RT-PCR, although in one of them, PET/CT allowed an early diagnosis of a lung infection related to a bacterial pneumonic infection that was promptly and adequately treated with antibiotics.

Conclusion: These results confirm that the prevalence of SARS-CoV-2 infection is higher than suspected and that there are asymptomatic patients that are attending imaging departments to be explored for their baseline oncologic processes. In these patients, PET/CT allows an early diagnosis of COVID-19.

Keywords: COVID-19; Cancer; Coronavirus; FDG PET/CT; Oncologic indications; RT-PCR.

Fig. 1

A 65-year-old male patient with locally advanced rectal cancer who came for [¹⁸F]-FDG PET/CT for initial staging. Axial, sagittal and coronal CT slices (a) and fused [¹⁸F]-FDG PET/CT (b) show the most frequent imaging finding in COVID-19 patients; this is GGOs (black arrows) coinciding with an area of intense [¹⁸F]-FDG uptake, peripherally localised, with an homogeneous [¹⁸F]-FDG uptake

Fig. 2

A 72-year-old female patient who was referred for [¹⁸F]-FDG PET/CT for initial staging of ovarian cancer. Axial CT (a) and fused [¹⁸F]-FDG PET/CT (b) show GGOs coinciding with an area of intense [¹⁸F]-FDG uptake in the left lung and a low uptake in the right lung, corresponding to a quickly resolved infiltrate

Fig. 3

A 66-year-old female patient with head and neck tumour, referred for [¹⁸F]-FDG PET/CT for suspected recurrence. Axial CT (a and b) and fused [¹⁸F]-FDG PET/CT (c and d) show extensive disease in both lungs with pleural effusion (broad arrow), hilar infiltrates (arrow heads) and nodules (long arrows). GGOs were also present in this patient but are not included in the image presented

Fig. 4

Maximum intensity projections (MIPs) with the same SUV scale of the seven patients that were considered suspicious for SARS-CoV-2 infection based on the [¹⁸F]-FDG PET/CT findings